Edouard Claparède was born and spent most of his life in Geneva. After studying science and medicine he concentrated on psychology, studying, and later collaborating, with Theodore Fluornoy, to whom he was closely related. Claparède succeeded Fluornoy as Professor of Psychology at the University of Geneva in 1915, a post he held until his death. His psychological interests were broad, including such topics as sleep, intelligent action, problem solving and education. He also maintained interests in neurology and psychiatry. As well as theoretical, experimental and applied work in psychology, Claparède devoted considerable time to professional and organizational activities. He co-founded with Flournoy the journal Archives de Psychologie, and contributed significantly to the international co-operation of psychologists through the International Congress of Psychology. In addition he founded (in 1912) the Institute J.J. Rousseau as a centre for innovative research and practice in education, and subsequently home to much of the work of Jean Piaget.

Throughout his wide range of interests, Claparède insisted on the importance of function. For example, his approach to the topic of sleep was to treat it as a positive state, interrelated with the need for the organism to protect itself against fatigue. He argued that there must be an active inhibition of activity, under neural control. Withdrawal of contact with the sensory world — a condition that he suggested was also the case in hysteria — must take place for functional reasons. Indeed the notion of contact between the organism and its environment was central to Claparède's thinking, linking it conceptually to the ideas of the pragmatist approach, as illustrated by his ‘Law of Becoming Conscious’. This proposal was a complex one which made a number of different predictions. It stated that mental activity does not emerge into consciousness so long as it is succeeding in its function. Like the instincts, cognitive processing may be effective without resource to consciousness so long as it is succeeding in its function. Only if some new demand is imposed by the environment will the mental processes be ‘grasped’ by consciousness. Acquired experience may then be brought to bear on the problem and appropriate adjustments of action made. This dynamic approach to consciousness owed something to Claparède's long-standing interest in the claims of psychoanalysis as well as the findings of comparative psychology. It gave rise to an experimental method in which the research subject provided verbal protocols as problem solving took place. This method gave Claparède's research some of the characteristics of the cognitive psychology of more recent times.

A second aspect of the ‘Law of Becoming Conscious’ is the developmental one. Claparède argued that processes which are employed earliest in development, without the necessity for conscious awareness of them, are the latest to be grasped by consciousness. That is to say, ‘the earlier and the longer a relation has been in use, the later it is consciously perceived’. His own chief example was resemblance. Thus the infant acts on the basis of resemblance between objects and situations, but becomes consciously aware of resemblance long after becoming conscious of difference. This developmental hypothesis, like many other aspects of Claparède's Law and of his other claims, received careful attention from Piaget. Its corollary seems particularly provocative, for if we could agree on what the latest (most mature) developmental achievements might be, this would offer fascinating possibilities for the understanding of infancy. Logical implication, for example, might be thought of as a late achievement in conscious awareness. If so, the corollary of Claparède's Law would predict that non-conscious employment of logical implication must be among the earliest of cognitive capabilities. It should be stressed that Piaget's work does not exhaust the potential of Claparède's Law of Becoming Conscious, or of his other suggestions. Indeed Claparède often seems to have taken a more dynamic, open-ended approach to cognitive development than his younger colleague. Claparède's approach was always open-minded, constantly attempting to recognize the fluidity of human action in its relationship with the environment.